Probably, when you are creating web parts for a certain product or company you want to include the logo instead of using the Office UI Fabric font. You could do this by uploading your image and adding the URL of the image to the iconImageUrl property.

But did you know that you can also make use of Base64 encoded images?

Base64 what?

Instead of specifying an URL to an image to load, you can encode your image. That way you do not have to upload your image to an online location, and there is no extra request necessary to retrieve the image.

For example, this image:

PnP SharePoint

Becomes this:

PnP SharePoint encode image

The great thing about it is that you can maintain everything in one location and do not have to worry about where you are going to store the icon images.